Microstructure and mechanical properties of carbide-reinforced Ta-W-based refractory medium-entropy alloys prepared by spark plasma sintering

The inversion of room-temperature compression plasticity and high-temperature strength in refractory high-entropy alloys poses a significant challenge for practical applications. In this study, a carbide-reinforced Ta-W-based refractory medium-entropy alloy was fabricated using spark plasma sintering. The alloy exhibits outstanding room-temperature compression plasticity and excellent high-temperature strength. Its microstructure consists of a BCC matrix with M₂C carbides, with nano-scale HfO₂ particles dispersed within the BCC matrix. The M₂C carbides are micron-sized, with visible metal matrix interlayers between them. Effective control over the oxide content, as well as the size and distribution of the oxides and carbides, is crucial for achieving superior plasticity in the alloy. At room temperature, the alloy achieves a fracture strain of 20 %, surpassing similar composition alloys produced by arc melting. Furthermore, the strengthening effect of carbides significantly enhances the high-temperature strength of the alloy, resulting in a yield strength of 352 MPa and an ultimate compressive strength of 426 MPa at 1750 °C. However, due to the specific composition and spatial characteristics of the carbides, its strength is slightly lower than that of arc-melted counterparts with similar compositions. This study successfully demonstrates the feasibility of fabricating carbide-reinforced refractory alloys that integrate high room-temperature compression plasticity with strong high-temperature performance. The proposed method offers a promising approach for the large-scale production of refractory alloy components, underscoring its potential for practical applications.